Dear, you said this car was for babies and you did not want it. She said she wanted it, and you agreed. Once you handed it to her, it was hers. It was a gift.
A gift, when viewed through a legal lens, requires: delivery; donative intent; and acceptance. Delivery can take many shapes and forms (there are volumes of case books on the topic), but requires the element of surrender. And with that comes the cold harsh reality that once given, the giftor cannot control how the giftee uses item. For my son that meant his sister was free to put the car down for a nap instead of turn it into a rocket, per his wish. For my clients it often means giving a gift to an adult child, and accepting that the adult child can do whatever he or she desires (share with a spouse, gamble away, etc.). Donative intent generally is based on the giving persons words, but the courts can infer it from behavior as well. Acceptance happens when the new party, well accepts the gift. Until acceptance has been made a gift can be revoked, but not after.
In our living room I pointed out that the car was given as a gift (it was for babies in his mind), no money was exchanged, and his sister gladly accepted the toy into her fold. No longer able to be revoked, it was hers, and it was taking a nap, not blasting into space. My 4 year old was put off a bit by my legal lesson, as are some of my clients at times. Realizing control is gone, and watching something that was once yours be used in a way you disagree with can be hard to stomach at times. Lawyers -- we do not always deliver the words our clients, or children, wish to hear.
His Toy Bin -- Image Taken by Ian. G. Gervasi, 2013, age 4